**Part 5**

**The Interaction of the Solar Wind with the Magnetosphere** 

314 Exploring the Solar Wind

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2011.

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*USA*

**Impact of Solar Wind on the Earth**

**of Ring Current and Radiation Belts**

Natalia Buzulukova1, Mei-Ching Fok2 and Alex Glocer2

<sup>2</sup>*NASA Goddard Space Flight Center*

**Magnetosphere: Recent Progress in the Modeling**

When solar wind interacts with the Earth's magnetosphere it causes disturbances in the near-Earth plasma environment. Large disturbances result in geomagnetic storms, and affect not only Earth magnetosphere but also space-borne and ground-based technological systems. The systematic studies of cause-effect relations between solar wind variations and resulting disturbances in near-Earth plasma environment as well as the construction of relevant numerical models are important subjects of *Space Weather*, which is currently a very

A most common reaction of the magnetosphere to prolonged solar wind disturbances are geomagnetic storms. Understanding geomagnetic storms and their solar wind drivers is one of the most important problems in geophysics and space weather. A geomagnetic storms is defined by a deviation of the H component of the Earth's magnetic field at low latitudes, i.e., the Dst index. It is believed that the main source of this deviation is the so called ring current which is comprised of plasma with energies 1–200 keV. Hence, to understand geomagnetic storms, we need to understand how the ring current is formed. Many previous studies have addressed the question of solar wind drivers for geomagnetic storms. Most of these were statistical in nature (Borovsky & Denton, 2006; Denton et al., 2006; Turner et al., 2009; Weigel, 2010; Yermolaev et al., 2010; Zhang, Richardson, Webb, Gopalswamy, Huttunen, Kasper, Nitta, Poomvises, Thompson, Wu, Yashiro & Zhukov, 2007). They focused upon the effectiveness of different types of solar wind structures in producing geomagnetic disturbances (e.g., a combinations of global activity indices and/or various

In addition to statistical analysis, a great deal of effort has been put into the development of ring current models. Typically a kinetic approach is used in which modeling ring current plasma is described with a number of species. Each population has its own energy and drift velocity which is a sum of the gradient/curvature drift and E×B drift. Plasma in this representation is generally anisotropic and is not in a thermodynamic equilibrium. The corresponding transport equations are usually written in terms of bounce-averaged quantities. This approach is sometimes referred to as 'drift physics' approach and has proven to be very useful in describing the plasma population of inner magnetosphere with energies

**1. Introduction**

active topic of research.

coupling functions) and different types of storms.

<sup>1</sup>*NASA Goddard Space Flight Center/CRESST/University of Maryland College Park*
